ManagementThere are two aims in the management
of retinal vein occlusion: the identification of modifiable risk
factors and their medical management and the recognition and management
of sight-threatening complications.

Although the systemic investigation
and treatment in all types of vein occlusion is similar, the ophthalmological
management of branch and central retinal vein occlusion differs.
These will therefore be considered separately.

OPHTHALMOLOGICAL MANAGEMENT

4.1 Central retinal vein occlusion

There
is no proven early treatment that will alter the visual prognosis in established central retinal vein
occlusion. The main management problem is to differentiate ischaemic
from non-ischaemic central retinal vein occlusion. Patients with ischaemic
CRVO are at risk of neovascular glaucoma for which laser photocoagulation
may be beneficial. This risk of iris neovascu-larisation is higher if the area
of retinal ischaemia (retinal non-perfusion as determined by FFA) is >10
disc diameters (CVOS).18
Ischaemic central retinal vein occlusion is associated
with one or more of the following characteristics:-

There is no evidence as to which combination
of the above characteristics best defines ischaemic CRVO. It
is important to note that up to 30% of patients with initially nonischaemic
central retinal vein occlusion will develop ischaemic transformation.24-
27This is usually heralded by further
rapid visual deterioration and requires further assessment. CRVO especially
of the non-ischaemic type needs to be differentiated from the ocular
ischaemic syndrome and other simulating retinopathies..4.1.1 Management of ischaemic
central retinal vein occlusion and anterior segment neovascularisation
An initial evaluation of risk factors and the appropriate treatment of the present risks must proceed alongside
management of the ocular findings.The evidence supports the use of
laser pan-retinal photocoagulation when iris new vessels (INV) or angle
new vessels (ANV) are visible. Monthly follow up is advised for
six months in all untreated patients with features of retinal ischaemia and
must include undilated pupil examination and detailed examination of the
iris with gonioscopy.18
(However, this monthly follow up may be impracticable
in some UK eye clinics). PRP should be applied at the earliest sign
of INV and or ANV..
In circumstances when regular follow-up is impractical, prophylactic treatment may be appropriate.28..4.1.2 Posterior segment neovascularisation
This is an uncommon complication following ischaemic central retinal vein occlusion in eyes which have
not developed neovascular glaucoma or who have been successfully treated
for rubeosis by laser. It has been reported that this complication
does not usually require active therapy.29..4.1.3 Pan-retinal Photocoagulation
Technique
Pan-retinal photocoagulation for CRVO with INV or ANV requires 1500 - 2000 of 500-micron burns
at the retina. This is best applied with 0.05-0.1 seconds applications one
burn width apart with sufficient energy to produce a pale burn in the retina.
Treatment is usually placed in the periphery avoiding areas of retinal
haemorrhage. Some cases require further treatment if the iris neovascularisation
fails to regress.18.
There is an alternate view to the management of irisneovascularisation. There is a suggestion
that rubeosis does not inevitably lead to glaucoma and therefore laser
photocoagulation should be withheld because this treatment leads to further
contraction of the visual field.30 However, it is our opinion
that the weight of evidence supports the recommendations stated above.18,28,31.4.1.4 Management of established
neovascular glaucoma
The aim of management of this condition in a blind eye is to keep the eye pain free. This is usually achieved
by topical steroids and atropine. However, if the eye has any visual
potential intraocular pressure should be controlled with topical pressure-lowering
agents or cyclo-ablative procedures. Drainage procedures
are of limited value..4.1.5 Macular oedema
Macular oedema following central retinal vein occlusion results from leakage of perifoveal capillaries.
It results in visual loss but there is no proven treatment for this condition.
Randomised controlled trials have failed to indicate benefit from
grid treatment, although a trend in favour of treatment has been observed in
younger patients.32
Although there was significant reduction in the
severity of macular oedema in treated eyes compared to controls there
was no visual acuity benefit..4.2 Recommendations for Further
Follow-up
Follow-up after 6 months for ischaemia (> 10DD non-perfusion) should be every 3 months for 1 year. Non
ischaemic eyes should have initial follow up every 3 months for 6 months.
Subsequent follow-up for all patients will depend upon laser treatment and
complications but will not normally be required after 2 years in uncomplicated
cases. The development of disc collaterals +/- resolution of the
CRVO should lead to discharge from clinical supervision..Experimental treatments
Chorio-retinal anastomosis is an experimental treatment and the results of randomised trials of this therapy
are awaited. However, there are significant complications associated
with laser-assisted chorioretinal venous anastomosis eg choroidal neovascularisation33,
retinal and subretinal fibrosis or traction34,and
vitreous haemorrhage.35.
Trials of other treatments such as radial optic neurotomy with pars plana
vitrectomy, and thrombolytic therapies are under way. These, however, are only experimental at present and
are, therefore, not recommended except as part of clinical trials.